U.S. patent application number 10/213768 was filed with the patent office on 2004-02-12 for method and system for producing a wood substrate having an image on at least one surface and the resulting wood product.
Invention is credited to Daniels, Evan R., Hardesty, Jon H., Taylor, Dene H..
Application Number | 20040026017 10/213768 |
Document ID | / |
Family ID | 31494521 |
Filed Date | 2004-02-12 |
United States Patent
Application |
20040026017 |
Kind Code |
A1 |
Taylor, Dene H. ; et
al. |
February 12, 2004 |
Method and system for producing a wood substrate having an image on
at least one surface and the resulting wood product
Abstract
A method and system is provided for producing an image on one or
more surfaces of a wood or wood composite substrate by applying a
receptor coat to at least the one or more surfaces of the
substrate, transferring the image to the receptor coat using a
variety of image transfer processes and applying a topcoat to the
image and receptor coat. The system implements the above method
using a series of stations and includes a series of platens
connected together by a chain and a set of rollers that allow the
substrate to travel through the stations on the platens. The
resulting wood or wood composite product includes a substrate, a
receptor coat disposed on one or more surfaces of the substrate, an
image disposed on or within the one or more surfaces of the
receptor coat and a top coat disposed on the image and receptor
coat.
Inventors: |
Taylor, Dene H.; (New Hope,
PA) ; Hardesty, Jon H.; (Dallas, TX) ;
Daniels, Evan R.; (Dallas, TX) |
Correspondence
Address: |
HAYNES AND BOONE, LLP
901 MAIN STREET, SUITE 3100
DALLAS
TX
75202
US
|
Family ID: |
31494521 |
Appl. No.: |
10/213768 |
Filed: |
August 7, 2002 |
Current U.S.
Class: |
156/230 ;
156/240; 156/277; 156/540; 428/913.3; 428/914 |
Current CPC
Class: |
B41M 5/0082 20130101;
B44C 5/0446 20130101; B44F 9/02 20130101; B41M 5/38221 20130101;
B44C 1/1712 20130101; B41M 7/0027 20130101; Y10T 428/14 20150115;
B44C 5/043 20130101; Y10T 156/1705 20150115; Y10T 428/24802
20150115; Y10S 428/914 20130101; B41M 5/38207 20130101 |
Class at
Publication: |
156/230 ;
156/240; 156/277; 156/540; 428/913.3; 428/914 |
International
Class: |
B44C 001/165 |
Claims
What is claimed is:
1. A method for producing an image on one or more surfaces of a
wood or wood composite substrate, comprising the steps of: applying
a receptor coat of powder to at least the one or more surfaces of
the substrate; curing the powder to adhere to the substrate;
transferring the image to the receptor coat; and applying a topcoat
to the image and receptor coat.
2. The method as recited in claim 1, wherein the substrate is a
panel.
3. The method as recited in claim 1, wherein the substrate is a
door.
4. The method as recited in claim 1, wherein the substrate is a
table top.
5. The method as recited in claim 1, wherein the substrate is a
counter top.
6. The method as recited in claim 1, wherein the one or more
surfaces of the substrate are substantially planar.
7. The method as recited in claim 1, wherein a cross section of the
one or more surfaces of the substrate varies in one dimension.
8. The method as recited in claim 1, wherein a cross section of the
one or more surfaces of the substrate varies in two dimensions.
9. The method as recited in claim 1, further comprising the step of
preparing the one or more surfaces of the substrate.
10. The method as recited in claim 9, wherein the step of preparing
the one or more surfaces of the substrate includes shaping, edging,
forming, routing, drilling, creating hardware recesses, sanding or
cutting of the substrate.
11. The method as recited in claim 1, further comprising the step
of pre-finishing the one or more surfaces of the substrate.
12. The method as recited in claim 11, wherein the step of
pre-finishing the one or more surfaces of the substrate includes
cleaning, polishing, sanding, sealing, staining or fillcoating the
substrate.
13. The method as recited in claim 1, further comprising the step
of cleaning the one or more surfaces of the substrate
14. The method as recited in claim 1, wherein the image is
transferred to the receptor coat using a dye sublimation
process.
15. The method as recited in claim 1, wherein the image is
transferred to the receptor coat using an ink transfer process.
16. The method as recited in claim 1, wherein the image is
transferred to the receptor coat using a direct printing
process.
17. The method as recited in claim 1, wherein the image is
transferred to the receptor coat using a non-contact ink transfer
process.
18. The method as recited in claim 1, wherein the image is
transferred to the receptor coat using a lamination transfer
process.
19. A method for producing an image on one or more surfaces of a
wood or wood composite substrate, comprising the steps of: applying
a receptor coat to at least the one or more surfaces of the
substrate; bringing a transfer material containing the image to be
transferred in contact with the receptor coat; transferring the
image to the receptor coat by applying heat and pressure to the
transfer material to cause the ink of the image to adhere to the
receptor coat; and applying a topcoat to the image and receptor
coat.
20. A method for producing an image on one or more surfaces of a
wood or wood composite substrate, comprising the steps of: applying
a receptor coat to at least the one or more surfaces of the
substrate; transferring the image to the receptor coat using a
direct printing process; and applying a topcoat to the image and
receptor coat.
21. A method for producing an image on one or more surfaces of a
wood or wood composite substrate, comprising the steps of: applying
a receptor coat to at least the one or more surfaces of the
substrate; transferring the image to the receptor coat using a
non-contact ink transfer process; and applying a topcoat to the
image and receptor coat.
22. A method for producing an image on one or more surfaces of a
wood or wood composite substrate, comprising the steps of: applying
a receptor coat to at least the one or more surfaces of the
substrate; transferring the image to the receptor coat using a
lamination process; and applying a topcoat to the image and
receptor coat.
23. A system for producing an image on one or more surfaces of a
wood or wood composite substrate comprising: a receptor coating
station that applies a receptor coat to at least the one or more
surfaces of the substrate; an image transfer station that transfers
the image to the receptor coat; a top coating station that applies
a topcoat to the image and receptor coat; a series of platens
connected together by a chain; and a set of rollers that allow the
substrate to travel on one of the platens through the receptor
coating station, the image transfer station and the top coating
station.
24. The system as recited in claim 23, wherein the substrate is a
panel.
25. The system as recited in claim 23, wherein the substrate is a
door.
26. The system as recited in claim 23, wherein the substrate is a
table top.
27. The system as recited in claim 23, wherein the substrate is a
counter top.
28. The system as recited in claim 23, wherein the one or more
surfaces of the substrate are substantially planar.
29. The system as recited in claim 23, wherein a cross section of
the one or more surfaces of the substrate varies in one
dimension.
30. The system as recited in claim 23, wherein a cross section of
the one or more surfaces of the substrate varies in two
dimensions.
31. The system as recited in claim 23, further comprising a
substrate preparation station disposed prior to the receptor
coating station.
32. The system as recited in claim 31, wherein the substrate
preparation station shapes, edges, forms, routs, drills, creates
hardware recesses, sands or cuts one or more surfaces of the
substrate.
33. The system as recited in claim 23, further comprising a
pre-finishing station disposed prior to the substrate preparation
station.
34. The system as recited in claim 33, wherein the pre-finishing
station cleans, polishes, sands, seals, stains or fillcoats the
substrate.
35. The system as recited in claim 23, further comprising a
cleaning station disposed prior to the receptor coating
station.
36. The system as recited in claim 23, wherein the image transfer
station transfers the image to the receptor coat using a dye
sublimation process.
37. The system as recited in claim 23, wherein the image transfer
station transfers the image to the receptor coat using an ink
transfer process.
38. The system as recited in claim 23, wherein the image transfer
station transfers the image to the receptor coat using a direct
printing process.
39. The system as recited in claim 23, wherein the image transfer
station transfers the image to the receptor coat using a
non-contact ink transfer process.
40. The system as recited in claim 23, wherein the image transfer
station transfers the image to the receptor coat using a lamination
transfer process.
41. A wood or wood composite product comprising: a wood or wood
composite substrate; a receptor coat disposed on one or more
surfaces of the substrate; an image disposed on or within the
receptor coat; and a top coat disposed on the image and receptor
coat.
42. The wood or wood composite product as recited in claim 41,
wherein the substrate is a panel.
43. The wood or wood composite product as recited in claim 41,
wherein the substrate is a door.
44. The wood or wood composite product as recited in claim 41,
wherein the substrate is a table top.
45. The wood or wood composite product as recited in claim 41,
wherein the substrate is a counter top.
46. The wood or wood composite product as recited in claim 41,
wherein the one or more surfaces of the substrate are substantially
planar.
47. The wood or wood composite product as recited in claim 41,
wherein a cross section of the one or more surfaces of the
substrate varies in one dimension.
48. The wood or wood composite product as recited in claim 41,
wherein a cross section of the one or more surfaces of the
substrate varies in two dimensions.
49. The wood or wood composite product as recited in claim 41,
further comprising one or more pre-finishing layers disposed
between the substrate and the receptor coat.
50. The wood or wood composite product as recited in claim 49,
wherein the pre-finishing layers include polishes, sealants, stains
or fillcoats.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates generally to the field of
wood, wood composites, imaging on wood and wood composites, and
coatings for wood and wood composites. More specifically, the
present invention relates to a method and system for producing a
wood or wood composite substrate having an image on at least one
surface and the resulting wood or wood composite product.
BACKGROUND OF THE INVENTION
[0002] The diminished availability and high cost of hard woods for
use as furniture or attractive building materials has proliferated
the use of less expensive wood and wood composites. In many of
these cases, the less expensive wood and wood composites are
modified or finished such that they appear to be either natural
wood or a specific hard wood. In other cases, a decorative image,
logo or name is "printed" on the less expensive wood and wood
composites. Alternatively, inexpensive wood composites are surfaced
with colored or printed vinyl, phenolic-backed or similar
decorative laminates, but these laminates all show edges and cracks
or delaminate at these locations, and they are themselves costly.
Each existing process used to create these wood or wood composite
products has disadvantages and trade offs. For example, producing a
high quality wood or wood composite product substantially increases
plant and production costs while reducing throughput. Conversely, a
lower cost wood or wood composite product produced at a higher
throughput can be achieved by sacrificing quality and durability.
These problems are compounded if the wood or wood composite product
is non-planar.
[0003] There is, therefore, a need for a method and system that
produce a high quality, durable and economical wood or wood
composite substrate having an image on at least one surface.
Moreover, there is a need for such a method and system to be
implemented as a relatively high throughput production line process
that will work with both planar and non-planar substrates and
objects.
SUMMARY OF THE INVENTION
[0004] The present invention provides a method and system that
produces a high quality, durable and economical wood or wood
composite substrate having an image on at least one surface. In
addition, this method and system can be implemented as a relatively
high throughput production line process that will work with both
planar and non-planar substrates and objects. Moreover, the present
invention is applicable to a variety of coating processes, image
transfer processes and types of image to be transferred. The
specific coating and image transfer processes used are selected
based on the type of image to be transferred and the specifications
of the resulting wood or wood composite product. In all cases, the
present invention provides improved reliability and registration of
the image transfer. Inline processing also permits the imaging to
be performed on partly cured or gel-stage coatings, which can boost
production and image quality while simultaneously reducing
costs.
[0005] More specifically, the present invention provides a method
for producing an image on one or more surfaces of a wood or wood
composite substrate by applying a receptor coat of powder to at
least the one or more surfaces of the substrate, curing the powder
to adhere to the substrate, transferring the image to the receptor
coat and applying a topcoat to the image and receptor coat. Among
other things, the substrate can be a panel, door, door front, door
header, passage door, table top, counter top, tray, molding,
banister, baluster, valance, flooring, display, signage, plywood
cylinders, toys, shelving, picture frames, shudders, picture rails,
furniture, boards for ready to assemble furniture, cabinet, cabinet
box, pedestal, lectern, wall covering, panels and boards for
construction, trim, decorative article, or any other wood product
or object or part thereof. In addition, the one or more surfaces of
the substrate can be substantially planar, or have a cross section
that varies in one or two dimensions. The image can be transferred
to the receptor coat using a dye sublimation process, ink transfer
process, direct printing process, non-contact ink transfer process
or lamination transfer process.
[0006] In addition, the present invention provides a method for
producing an image on one or more surfaces of a wood or wood
composite substrate by applying a receptor coat to at least the one
or more surfaces of the substrate, bringing a transfer material
containing the image to be transferred in contact with the receptor
coat, transferring the image to the receptor coat by applying heat
and pressure to the transfer material to cause the ink of the image
to adhere to the receptor coat and applying a topcoat to the image
and receptor coat.
[0007] Alternatively, the present invention provides a method for
producing an image on one or more surfaces of a wood or wood
composite substrate by applying a receptor coat to at least the one
or more surfaces of the substrate, transferring the image to the
receptor coat using a direct printing process and applying a
topcoat to the image and receptor coat. A non-contact ink transfer
process or lamination process can be used in place of the direct
printing process.
[0008] Moreover, the present invention provides a system for
producing an image on one or more surfaces of a wood or wood
composite substrate. The system includes a receptor coating station
that applies a receptor coat to at least the one or more surfaces
of the substrate, an image transfer station that transfers the
image to the receptor coat and a top coating station that applies a
topcoat to the image and receptor coat. The system also includes a
series of platens connected together by a chain and a set of
rollers that allow the substrate to travel on one of the platens
through the receptor coating station, the image transfer station
and the top coating station.
[0009] The present invention also provides a wood or wood composite
product that includes a wood or wood composite substrate, a
receptor coat disposed on one or more surfaces of the substrate, an
image disposed on or within the receptor coat and a top coat
disposed on the image and receptor coat.
[0010] Other features and advantages of the present invention will
be apparent to those of ordinary skill in the art upon reference to
the following detailed description taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] For a better understanding of the invention, and to show by
way of example how the same may be carried into effect, reference
is now made to the detailed description of the invention along with
the accompanying figures in which corresponding numerals in the
different figures refer to corresponding parts and in which:
[0012] FIG. 1 illustrates an overall process for producing an image
on one or more surfaces of a wood or wood composite substrate in
accordance with the present invention;
[0013] FIG. 2 illustrates a more detailed process for producing an
image on one or more surfaces of a wood or wood composite substrate
in accordance with the present invention;
[0014] FIG. 3A illustrates a dye sublimation process for
substantially flat substrates in accordance with the present
invention;
[0015] FIG. 3B illustrates a cross sectional view of a product
produced by the dye sublimation process of FIG. 3A in accordance
with the present invention;
[0016] FIGS. 4A and 4B illustrate dye sublimation processes for
non-flat substrates in accordance with the present invention;
[0017] FIG. 4C illustrates a cross sectional view of a product
produced by the dye sublimation process of FIGS. 4A and 4B in
accordance with the present invention;
[0018] FIG. 5 illustrates an ink transfer process in accordance
with the present invention;
[0019] FIG. 6 illustrates a direct printing process in accordance
with the present invention;
[0020] FIG. 7 illustrates a non-contact ink transfer process in
accordance with the present invention;
[0021] FIG. 8 illustrates a lamination transfer process in
accordance with the present invention; and
[0022] FIGS. 9A and 9B illustrate cross sectional views of a
product produced by an ink transfer, lamination, direct transfer or
non-contact transfer process in accordance with the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0023] While the making and using of various embodiments of the
present invention are discussed in detail below, it should be
appreciated that the present invention provides many applicable
inventive concepts, which can be embodied in a wide variety of
specific contexts. The specific embodiments discussed herein are
merely illustrative of specific ways to make and use the invention
and do not limit the scope of the invention.
[0024] The present invention provides a method and system that
produces a high quality, durable and economical wood or wood
composite substrate having an image on at least one surface. In
addition, this method and system can be implemented as a relatively
high throughput production line process. Moreover, the present
invention is applicable to a variety of coating processes, image
transfer processes and types of image to be transferred. The
specific coating and image transfer processes used are selected
based on the type of image to be transferred and the specifications
of the resulting wood or wood composite product. In all cases, the
present invention provides improved reliability and registration of
the image transfer. Inline processing also permits the imaging to
be performed on partly cured or gel-stage coatings.
[0025] Referring now to FIG. 1, an overall process 100 for
producing an image on one or more surfaces of a wood or wood
composite substrate in accordance with the present invention is
shown. The process 100 begins in block 102 by providing a wood or
wood composite substrate for processing. The wood or wood composite
substrate may include Among other things, the substrate can be a
panel, door, door front, door header, passage door, table top,
counter top, tray, molding, banister, baluster, valance, flooring,
display, signage, plywood cylinders, toys, shelving, picture
frames, shudders, picture rails, furniture, boards for ready to
assemble furniture, cabinet, cabinet box, pedestal, lectern, wall
covering, panels and boards for construction, trim, decorative
article, or any other wood product or object or part thereof.
Moreover the one or more surfaces of the wood or wood composite
substrate can be horizontal or vertical (planar or substantially
planar), or vary in two dimensions (contoured, molded or profiled).
A wood composite substrate may include any type of man-made boards
of bonded wood sheets and/or lignocellulosic materials such as
veneer, fiberboard, particleboard, hardboard, waferboard,
cardboard, strandboard, plywood, or any combination of these
materials.
[0026] A receptor coat is then applied to at least the one or more
surfaces of the substrate in block 104. The receptor coat can be a
clear or opaque coating and is used to ensure a quality image
transfer to the substrate. Clear receptor coats can be applied
using a powder, a radiation curable liquid or traditional solvent.
The powder can be applied using various electrostatic processes.
The application of powder coatings typically requires the sub-steps
of preheating, coating, curing and cooling. The application of
radiation curable liquid coating requires the sub-steps of coating
and curing. The application of traditional solvent coatings
typically requires the sub-steps of coating and drying. Opaque
receptor coats can be applied using any of the following dual coat
process: a liquid base coat followed by a clear coat; an opaque
powder followed by a clear powder; an opaque radiation curable
liquid followed by a clear powder; or an opaque radiation curable
liquid followed by a clear radiation curable liquid. Opaque
receptor coats may include white or colored pigments. In addition,
opaque receptor coats can be applied using an integral pigmented
coating of powder, radiation curable liquid or traditional
solvent.
[0027] The material chosen for the receptor coat should exhibit a
moderate surface tension allowing "wetting" of the substrate
surface while subsequently allowing the ink/dye from the imaging
process and the topcoat to "wet" the receptor coat. In addition the
material should exhibit a sufficiently high glass transition
temperature (Tg) to prevent flow during the imaging process and the
topcoat curing process. Partial cure of the receptor coat may be
acceptable if receptor coat material Tg is sufficiently high. For
example, a material exhibiting a maximum Tg of 150.degree. C. may
be partially cured to a point at which the Tg measures 110.degree.
C. If the Tg of 110.degree. C. is sufficiently high, then the time
and energy saved by the reduction of 40.degree. C. provides a cost
savings. Further curing and subsequent processing can raise the
hardness to that required in the end use.
[0028] Thereafter the image is transferred to the one or more
surfaces of the substrate in block 106. The image transfer process
may include dye sublimation, ink transfer, direct printing,
non-contact printing or printing or preprinting saturated paper.
These processes will described in more detail in relation to FIGS.
3A-3B, 4A-4C, 5-8 and 9A-9B. The transferred image can be any
graphic, such as a picture, pattern or coloration, etc. The image
transfer process can be a registered (all imaged parts are the
same) or staggered (adjacent imaged parts vary) process. The ink or
dye used to transfer the image to the wood or wood composite
substrate should exhibit a surface tension lower than that of the
receptor coat and higher than that of the intended topcoat. In
other words, the ink should "wet" the receptor coat and the topcoat
should "wet" the ink.
[0029] A topcoat is then applied to at least the one or more
surfaces of the substrate in block 108 to provide the finished
product in block 110. The topcoat may be applied using powder,
radiation curable liquid, solvent or over-laminate. The topcoat
should be transparent, non-yellowing, durable and provide
sufficient adherence to the receptor layer. The topcoat may also
have either a flat or glossy appearance. The material chosen for
the topcoat should exhibit a sufficiently low surface tension to
"wet" both the ink or dye laid down in the imaging process and
those regions of the receptor coat that are not bearing ink or dye
from the imaging process. In addition, the chosen material should
exhibit acceptable adhesion to the ink or dye from the image
transfer process and the receptor coat so that the topcoat will not
"peel" or pull away from the ink or dye and the receptor coat. This
is one factor in maintaining the high quality of the resulting
product.
[0030] Alternatively, the topcoat may be chosen to be receptive to
stain so that the final color of the imaged part can be selected at
a later date. Such coating may then be separately over-coated with
a durable clear top coating formulation. It would need to be
sufficiently durable to withstand the rigors of stacking and
transportation, but these are less than those contemplated for the
topcoat in final use.
[0031] Proper cure conditions should be established for a through
(100%) cure. Since the topcoat is used as a protective coating, it
should exhibit maximal physical properties that are achieved only
at advanced curing stages (i.e., highest possible molecular weights
provide optimal mechanical properties). The material chosen should
also be capable of providing the necessary tensile and compression
strengths, mar and scratch resistance, etc. Moreover, appropriate
film thickness should be established for the intended use of the
resulting wood or wood composite product. A larger film thickness
will be required for objects receiving extensive physical contact
resulting in abrasion of the topcoat film. Appropriate application
conditions for the topcoat can be established once the appropriate
film thickness is established for the intended use of the wood or
wood composite product.
[0032] Now referring to FIG. 2, a more detailed process 200 for
producing an image on one or more surfaces of a wood or wood
composite substrate in accordance with the present invention is
shown. The raw wood or wood composite substrate 202 is prepared in
block 204 and pre-finished in block 206. Substrate preparation 204
may include such things as shaping, edging, forming, routing,
drilling, creating hardware recesses, sanding and/or cutting of the
raw wood or wood composite substrate 202. Substrate pre-finishing
may include such things as cleaning, polishing, sanding, sealing,
staining and/or fillcoat/sanding. Note that sealing the wood or
wood composite substrate 202 at this stage of the process can
reduce the thickness required for the receptor coat. Depending on
the substrate pre-finishing 206 performed, the substrate 202 is
cleaned in block 208 by any typical process, such as brush, vacuum,
air jets, ionized air, static bars or any combination thereof.
Thereafter, a receptor coat is applied to one or more surfaces of
the substrate in block 210. For example, the receptor coat can be
applied to two sides of the wood or wood composite substrate 202 by
sending it vertically through the coater to coat both sides in one
booth. The ends and sides of the substrate 202 can also be coated
during this process. Certain areas of the substrate 202 may require
a "touch up" depending on how the substrate 202 is transported
through the coater. Substrates in this orientation need to be
coated by powder or spray, whereas horizontally oriented substrate
may be coated also by roll or curtain methods.
[0033] As previously described, the receptor coat can be a clear or
opaque coating and is used to ensure a quality image transfer to
the substrate. Clear receptor coats can be applied using powder, a
radiation curable liquid or traditional solvent. The powder can be
applied using various electrostatic processes. The application of
powder coatings typically requires the sub-steps of preheating,
coating, curing and cooling. The application of radiation curable
liquid coating requires the sub-steps of coating and curing. The
application of traditional solvent coatings typically requires the
sub-steps of coating and drying. Opaque receptor coats can be
applied using any of the following dual coat process: a liquid base
coat followed by a clear coat; an opaque powder followed by a clear
powder; an opaque radiation curable liquid followed by a clear
powder; or an opaque radiation curable liquid followed by a clear
radiation curable liquid. Opaque receptor coats may include white
or colored pigments. In addition, opaque receptor coats can be
applied using an integral pigmented coating of powder, radiation
curable solvent or traditional solvent.
[0034] The image is then transferred to the one or more surfaces of
the substrate in block 212. The image transfer process may include
dye sublimation, ink transfer, direct printing, non-contact
printing or saturated paper. These processes will described in more
detail in relation to FIGS. 3A-3B, 4A-4C, 5-8 and 9A-9B. The
sequencing of the substrate 202 from the application of the
receptor coat 210 to the image transfer process in 212 will vary
depending on the type of image transfer process 212 used. For
example, whenever a dye sublimation imaging process is used, such
as is described below in reference to FIGS. 3A, 3B, 4A, 4B and 4C,
the immediate sequencing of the image transfer process 212 (dye
sublimation) immediately after receptor coating 210 takes advantage
of the energy imparted into the substrate 202 by the drying or
curing required in the receptor coating step 210. More
specifically, a powder receptor coating process 210 typically
raises the surface temperature of the substrate 202 to
250-350.degree. F. and the UV cure can raise the temperature to 150
to 250.degree. F. Note that the drying of conventional receptor
coatings can produce a similar result. It is well known that dye
sublimation transfer on hot substrates 202 proceeds more
effectively than on cool substrates 202, and gives a crisper more
uniform and higher density image in a shorter time, often at lower
temperature and/or pressure. Hence, preheating is commonly
practiced. As a result, the delivery of a hot part (substrate 202)
from the receptor coating process 210 presents the substrate 202 in
a preferred condition. Ink transfer can also benefit from the
substrate 202 being at greater than ambient temperature, but to a
lesser extent. There is little advantage for direct or non-contact
printing, yet saturation may require this to suitably liquefy the
saturating liquid.
[0035] The transferred image can be any graphic, such as a picture,
pattern or coloration, etc. The image transfer process 212 can be a
registered (all imaged parts are the same) or staggered (adjacent
imaged parts vary) process. The reality of the appearance of an
image or pattern can be enhanced when the surface is embossed with
a like pattern. This is especially true with wood grains. Patterns
can be readily embossed when the substrate surface is soft. This
occurs in the present invention described herein when the coatings
are either hot, and therefore soft, or when they are in the gel
form. As a result, the final surface can be embossed with an
embossing roll at the appropriate point in the process to produce a
surface texture that compliments the transferred image.
[0036] Note that if substrates 202 imaged by dye sublimation are
stacked one atop the other immediately after the image transfer
process 212, there is often an offsetting or ghosting of the image
on the face side to the rear side of the substrate 202. This effect
can be minimized by either chilling the substrate 202 so that the
dye is trapped in the solidified matrix, or by placing a barrier
material such as thick Kraft paper between the freshly imaged
substrates 202. Chilling is, therefore, an optional step, which may
be added to the system 200. The final topcoat, though, when well
cured serves a similar purpose. Indeed, its composition may be
chosen so that it is not a good solvent for the dye and so it will
serve to trap the dye at elevated temperatures, negating the need
for a barrier or a chiller.
[0037] Accordingly, the topcoat is applied to at least the one or
more surfaces of the substrate in block 214 to provide the finished
product in block 216. The topcoat may be applied using powder,
radiation curable liquid, solvent or over-laminate. The topcoat
should be transparent, non-yellowing, durable and provide
sufficient adherence to the receptor layer. The topcoat may also
have either a flat or glossy appearance. The topcoat may contain UV
light absorbing chemicals and anti-oxidants to protect itself and
the underlying image from degradation.
[0038] The processes 100 and 200 can be implemented in a horizontal
or vertical production line or combination of both. The horizontal
production line can be implemented as a series of platens connected
by a chain moving on rollers on a floor level track. The wood or
wood composite substrates are laid flat on the platen. In one
embodiment of a completely horizontal production line, the chain
moves the platen and wood or wood composite substrate through the
following stations:
1 Step 1. Loading Step 2. Cleaner Step 3. Pre-heater Step 4. Base
coat application Step 5. Base coat cure Step 6. Image Transfer Step
7. Top coating Step 8. Final cure Step 9. Unloading
[0039] Preferably, such production line will operate at a speed of
approximately 50 feet per minute with the wood or wood composite
substrates being spaced approximately 50 inches apart. The exact
operating speed and spacing will depend on the coating and image
transfer processes that are selected. Note that the present
invention is also applicable to low speed production lines often
used to produce specialty or single unit products.
[0040] As previously stated, the image transfer process 212 may
include any of the following processes: dye-sublimation transfer;
ink or toner transfer; lamination of a saturating (porous) printed
paper; direct printing (e.g., flexography, gravure or letterpress);
or non-contact printing (e.g., inkjet). For each imaging process
212 there are a large number of factors to take into account when
designing the process and developing the materials. Some of these
factors include: surface temperature during the imaging step; gel
degree of cure at the imaging step; base and top coating
formulation; residence time for transfer; pressure during transfer
or imaging; ink composition; carrier paper properties; printing
process for the transfer material; composition and properties of
the saturating printed paper; orientation of the wood or wood
composite substrate; support and registration of the wood or wood
composite substrate; yield and scrap propensity; number of surfaces
to be imaged; and productivity. The differences of these imaging
processes are further illustrated in the following table:
2 Imaging Dye Ink Direct Non- Process Sublimation Transfer Contact
Contact Receptor Chemistry Polyester, Wide Wide Wide Polyamide
Variety Variety Variety Surface Smooth Moderately Smooth Any
Properties Solid Smooth Solid Solid Temperature Very Hot Moderately
Ambient to Ambient Hot Warm Donor Paper or Flexible Paper with Ink
Print Print (Image Carrier) film with disperse Compliant Roll Head
dye image Backing Hard Backing Backing Process Control Time 30 sec.
0.1 sec. 0.1 sec. Varies (5 to 100 sec.) Temperature 200.degree. C.
100.degree. C. to Ambient Ambient (150.degree. C. to 200.degree.
C.) 150.degree. C. Pressure 20 psi 10 pli Low None (1 to 500 psi)
Other Steps Separate Paper Separate Paper Dry Dry Issues Relatively
Slow Fragile One Color Print Uniform Contact Transfer At A Time
Head Size Material Uniform Nozzle Contact Clogging
[0041] Consequently, it can be seen that each imaging process will
have its advantages and disadvantages.
[0042] Dye sublimation printing is named for the dyes used--these
dyes will enter the gas phase at elevated temperature, and so
become very mobile. When adjacent to a material in which they are
very soluble, the dyes will migrate there. For example, polyester
at 350.degree. F., above its glass transition temperature, is an
excellent receptor for these dyes. Articles made from or coated
with polyester, polyamides and similar polymers, can be imaged by
dye sublimation. The imaging is carried out by first printing the
image in mirror form onto a donor or transfer sheet, usually paper,
laying the paper on to the polyester layer, then pressing the
sandwich at elevated temperature for a suitable time. An example of
the process conditions typically used for imaging hot rigid
substrates is 30 to 60 seconds at 400.degree. F. at 10 psi.
[0043] Typical conditions for dye sublimation imaging hot rigid
substrates are 20 to 60 seconds, 400.degree. F., 10 psi. There are
three primary processes for the transfer: flat bed, continuous belt
and rotary presses. The flat bed press is used solely for piece
goods, both flexible and rigid. Continuous belt presses, such as
described below in reference to FIGS. 3A and 4B, may be used for
both piece and web goods. They are particularly suited for piece
goods being imaged from web transfer paper. Rotary presses are
suitable only for flexible substrates whether piece or continuous.
In the flat bed press, such as described below in reference to FIG.
4A, the sandwich of the substrate and the printed transfer paper is
placed between the platens of the press. The top platen is always
heated--the bottom may be also, and is typically heated when the
substrate is prone to warpage from uneven top and bottom heating.
It may also assist with the rate of dye transfer. The press is
closed for the required duration and the transfer proceeds. On
opening the paper is removed from the substrate and the substrate
from the press. Presses are typically loaded and unloaded manually,
although automated systems are available. The continuous belt press
comprises two endless belts each rotating about two rollers. The
belts are mounted so that one is directly above the other, and the
top of the lower belt is in close proximity to the bottom of the
belt. The two belts are driven in opposite rotation so that where
they meet they run together. Pressure is applied to the belts in
the area between the drive rolls by pads or rollers. The rollers
and the pressure device may also apply heat, or the whole assembly
may be heated. Image transfer is affected by passing the sandwich
of the printed transfer paper and the substrate through the press.
Both piece goods and continuous webs may be processed. Loading and
unloading are typically automatic. Belt presses are preferred for
high volume production.
[0044] Referring now to FIG. 3A, a dye sublimation process 300 for
substantially flat substrates 302 in accordance with the present
invention is shown. The process includes a continuous belt press
having an upper endless metal belt 304 wrapped around first and
second upper hot rollers 306 and 308, and a lower endless metal
belt 310 wrapped around first and second lower rollers 312 and 314,
all of which are contained within an oven (not shown). The first
and second lower rollers 312 and 314 may or may not be heated to a
small degree, so that a realistic finish is achieved when the edges
and ends of a substrate are also receptor coated and imaged. Indeed
this attribute distinguishes this invention from both veneer and
lamination, which must show edge joints. A donor or transfer
material 316 is unwound from a supply roll 318, transported through
the oven via contact with the upper endless metal belt 304 and
rewound on take up roll 320. The donor or transfer material 316 is
a paper, fabric, PET film or other suitable medium in either sheet
(good for pictures) or web (good for continuous repeating patterns)
form containing dyes 322 representing the images to be transferred.
Web offset printed paper or transfer material 316 offers pictures
on a web and may be preferred for certain high volume applications.
In addition, there are a variety of digital and traditional
processes for the initial printing of the transfer material
316.
[0045] Registration of the image on the substrate 302 is a frequent
requirement. For this, the transfer material 316 is typically
provided with registration marks that can be distinguished by
automated systems and used to control the position of the transfer
material 316 relative to the substrate 302. Such systems are
available and well known. The pattern-repeat distance on continuous
pattern transfer material 316 is typically different from the
dimensions of the substrate 302. At the operator's option, the
registration can be adjusted so that the images on all substrates
302 are identical, or the registration can be staggered or
randomized so there is continual variability in the placement of
the pattern on the substrates 302. In particular, processing the
substrate 302 so that the short edge is parallel to the chain
direction may ensure that where the repeat distance is long, there
is no visible repeating pattern of the image on the substrate 302.
This is considered advantageous for the production of wood grain
and other natural patterns. The availability of digitally printed
dye sublimation transfer material 316 allows short runs,
demonstrations, prototype manufacture and proofing using this
process to be relatively inexpensive. Yet, because the transfer
material 316 can also be printed by flexography, gravure or offset
it is also very economical for very large production runs. If two
sided imaging is desired, a second donor or transfer material 324
is unwound from a supply roll 326, transported through the oven via
contact with the lower endless metal belt 310 and rewound on take
up roll 328. In this case, the first and second lower rollers 312
and 314 should be heated.
[0046] The wood or wood composite substrate 302a, which comprises
at least a base substrate 330 and receptor coat 332, enters the
image process 300 at point A. As the substrate passes though the
image process 300, the donor or transfer material 316 is heated and
pressed against the receptor coat 332 by the upper endless metal
belt 304 wrapped and the first and second upper hot rollers 306 and
308. The lower endless metal belt 310 and the first and second
lower rollers 312 and 314 maintain pressure against the base
substrate 330. Good contact between the transfer material 316 and
the receptor coating surface 332 is required, which may be
difficult to achieve if the surface is rough or aged. At point B,
the dye 322 is transferred to and permeates the receptor coat 332
in gaseous form 334. At point C, the wood or wood composite
substrate 302b exits the process having an image 336 within the
receptor coat 332. Residual dye components 338 remain on the donor
or transfer material 316.
[0047] The dye sublimation process 300 produces images that are
very vivid and crisp. In addition, the image adds no real thickness
and does not stand above the surface, which is a deficiency of
direct printing. As a result, the surface is usually little changed
by the imaging process. The gamut is wide and the selection of
graphics is extremely broad. This image transfer process can be
used to transfer images to both the top and bottom of horizontal
wood or wood composite substrate at same time. In addition, both
sides at can be done at one time, and both ends can be done at
another time. As a result, putting separate images on all these
surfaces will make a more realistic wood imitation. The image can
be applied cross-wise on the wood or wood composite substrate so
that there will be no repeat pattern visible on any substrate.
Staggering the start point will allow subsequent substrates to be
different rather than duplicates. Note that the image can wrap
edges and ends to a small degree.
[0048] For example, the printed transfer paper or material 316 is
normally wider than the substrate 302 to be imaged. When using
either dye sublimation or ink transfer (FIG. 5), the excess width
may be chosen so that it is greater than the depth of the side of
the substrate 302. The transfer material 316 can, therefore, be
wrapped around the side and processed in a like manner to the first
surface so that the image is transferred onto the sides of the
substrate 302. In this way, three of the six faces of a substrate
302 can be imaged in one process sequence. Should the two primary
faces of a substrate 302 need to be imaged, then the sealer (if
any) and receptor coating 332 should be applied to both faces. The
image is then transferred to the first face by the method selected
from those described herein, the substrate 302 is flipped and the
second surface imaged by whichever method is most appropriate for
the second face. The substrate 302 then moves on to top coating. If
four of the six faces of the substrate 302 are to be imaged, then a
sequence of imaging the first face, the first two sides, flipping
the substrate 302 and then imaging the final face can be followed.
If required, the substrate 302 can be rotated through 90 degrees so
that the ends can be imaged by a similar process. The substrate
then moves on to top coating.
[0049] If the substrates are moved with the short edge parallel to
the chain direction, there need be no repeating pattern visible on
any part as long as it is sufficiently small, such as 36 inches.
Changing the register of the print on the board can be used to make
each top a little bit different in appearance. Short runs,
demonstration, prototype manufacture and proofing using this
process are relatively inexpensive. Note that the relatively long
dwell time required for the diffusion of the dye 322 from the
transfer material 316 into the receptor coat 332 makes continuous
belt transfer presses preferable for large volume production of
large items as contemplated in this invention. Alternatively, flat
bed presses with automated loading and unloading may also be used
for high volume production if they operate at very high pressure so
that the rate of diffusion of the dye 322 is accelerated.
[0050] To ensure a good quality image, the receptor coat should be
made of polyester, polyamide or coated with polyester, polyamide or
a similar material. Formulations that accept disperse dyes are well
known. The dye sublimation process 300 allows the use of receptor
coat formulations that function at 300 to 350.degree. F., rather
than 400.degree. F. if the ink on the transfer material 316 and the
press conditions are optimized. Such formulations tend to be soft
and tacky, or in the so-called gel state. Often the receptor coat
332 is incompletely or only partially cured. Typically, the
transfer material 316 will become irreversibly bonded to the
receptor coat 332 during the image transfer press step. This may be
prevented by laying a very thin film of, polyethylene for example,
on the surface of the receptor coat 332 before the image is
transferred. The film is removed after the image transfer with the
used transfer material 316. Alternatively the ink layer 332 on the
printed transfer material 316 can be over coated with a thin layer
of film forming material that also allows the sublimation dye to
pass through, but which will not itself adhere to the receptor coat
332 in its gel or soft state. Moreover, the substrate and coatings
must stand high temperatures for extended times. The process is
also relatively slow compared to some of the other image processes.
Metallic colors do not reproduce very well using this process.
Furthermore, disperse dyes, are sensitive to UV induced fade. Note
that the image properties are not all discernible on the transfer
paper--transfer onto the receptor of choice is necessary.
[0051] Now referring to FIG. 3B, a cross sectional view of a
product 350 produced by the dye sublimation process 300 of FIG. 3A
in accordance with the present invention is shown. The finished
product 350 includes a base wood or wood composite substrate 352
that has a layer of stain 354 on the top surface of the substrate
352 and a layer of sealant 356 on the top surface of the stain
layer 354 and the sealant layer 356 are optional layers applied
during the substrate pre-finishing process 206 (FIG. 2). The
receptor coat 358 is applied to the top surface of the sealant
layer 354 during the receptor coating process 210 (FIG. 2). As
described in reference to FIG. 3A, the dyes 360 forming the desired
image are within the receptor coat 358. The topcoat 362 is then
applied on the top surface of the receptor coat 362 during the top
coating process 214 (FIG. 2). The receptor coat 358, dyes 360 and
topcoat 362 are required for the present invention. Although
reference is made to the top surface of the various layers, the
applicable surface is any portion of the base substrate 352 on
which an image is to be transferred. In other words "top surface"
could actually refer to the top, bottom, sides, ends or other
surface of the base substrate 352. In addition, the layers
described above may apply to some or all surfaces of the base
substrate 352.
[0052] Referring now to FIGS. 4A and 4B, dye sublimation processes
400 and 450 for non-flat substrates 410 and 468 in accordance with
the present invention is shown. Non-flat substrates 410 and 468 can
be separated into two categories--those with consistent
cross-sections in the direction of process flow, such as moldings
and trims, and those with cross-sections that vary in both the
direction of process flow, and across the direction of process
flow, such as panel doors and routed drawer fronts. As shown in
FIG. 4A, an image can be produced by process 400, which includes a
flat bed press having a heated top platen 402 and a bottom platen
402. The top platen 402 is substantially planar except for a long
stationary transfer nip, protrusion or reverse impression 406. The
transfer nip 406 is a long heated molded plate that conforms in
cross-section closely to the cross-section of the substrate 410
(including recess 408). The top platen 402 and transfer nip 406 are
preferably, but not necessarily, coated with a non-stick material,
such as Teflon.RTM., to allow the non-flat substrate 410 to move
smoothly.
[0053] The non-flat substrate 410 includes base substrate 412 and
receptor coat 414. The recess 408 can be any multi-dimensional
surface, such as moldings or trims, as long as proper contact and
pressure can be maintained to transfer the image. Moreover, the
term recess can included multi-dimensional surfaces that extend
above the "main" surface of the substrate 410. A donor or transfer
material 416 is unwound from a supply roll 418, transported along
the upper platen 402 and rewound on take up roll 420. The donor or
transfer material 416 is a paper, fabric, PET film, or other
suitable medium in either sheet (good for pictures) or web (good
for repeating patterns) form containing dyes 422 representing the
images to be transferred. Note that the type of transfer material
416 will depend greatly on the complexity of the recess 408 and the
image to be transferred. It may be advantageous to use a treated
transfer material 416 so that its side in contact with the top
platen 402 contains slip and non-stick agents. Such materials are
well known. When the substrate 410 has a consistent cross-section
in the longitudinal direction, paper is the preferred transfer
material 416 because it is not required to, and preferably should
not, stretch. As a result, paper will not be a good transfer
material 416 for most three-dimensional recesses 408.
[0054] Once the substrate 410 is properly positioned within the
press, the top platen 402 descends and forces the transfer material
416 into contact with the receptor coat 414 to transfer the image
at specific time, temperature, and pressure. The dye 422 is
transferred to and permeates the receptor coat 420 in gaseous form.
Residual dye components 424 remain on the donor or transfer
material 416. On exiting the transfer zone the transfer material
416 is removed by mechanical or vacuum means. It may be
advantageous to slit the transfer material 416 and use two or more
removal flows for higher process efficiency. The substrate 410 at
this point is imaged and ready for top coating.
[0055] With respect to FIG. 4B, the process 450 includes a Hymmen
press having an upper endless metal belt 452 wrapped around first
and second upper hot rollers 454 and 456, and a lower endless metal
belt 458 wrapped around first and second lower rollers 460 and 462,
all of which are contained within an oven (not shown). The first
and second lower rollers 460 and 462 may or not be heated. The
upper endless metal belt includes one or more protrusions or
reverse impressions 464 that are designed to mate with the recess
466 in the non-flat substrate 468. The non-flat substrate 468
includes both substrate 470 and receptor coat 472. The recess 466
can be any multi-dimensional surface, such as moldings, routing, or
insets, as long as proper contact and pressure can be maintained to
transfer the image. Moreover, the term recess can include
multidimensional surfaces that extend above the "main" surface of
the substrate 468. A donor or transfer material 474 is unwound from
a supply roll 476, transported through the oven via contact with
the upper endless metal belt 452 and rewound on take up roll 478.
The donor or transfer material 474 is a paper, fabric, PET film or
other suitable medium in either sheet (good for pictures) or web
(good for repeating patterns) form containing dyes 480 representing
the images to be transferred. As described in reference to FIG. 3A,
two sided imaging can be accomplished using a second donor or
transfer material (not shown) and the lower endless metal belt 458,
and first and second lower rollers 460 and 462. In addition, the
actual image transfer mechanism is the same as described in
reference to FIG. 3A, including dyes 482 in gaseous form and
residual dye components 484.
[0056] Alternatively, the upper endless belt can be replaced with a
device, which ensures proper transfer material to receptor coating
contact for the required dwell at a suitable pressure and
temperature. The device may include one or more rollers shaped to
match the profile of the substrate being imaged and operating at
suitable pressure and temperature. The additional steps required to
ensure the transfer material conforms to the substrate contours are
preferentially completed before the high temperature transfer step
begins. A continuous web transfer material works especially well
for this process. The transfer material is unwound from the supply
roll and fed through a series of angled compliant rollers so that
its shape is gradually brought to match that of the substrate
cross-sectional topography. An extended series of rolls is
preferred when the features of the substrate are deep and/or steep,
so that the transfer material is molded to the substrate in a
series of small steps. This avoids creasing or wrinkling. When the
transfer material is properly fitted to the substrate, the
resulting sandwich can then be pressed by the molded platen of a
stationery press as shown FIG. 4A, or by a continuous transfer
press as shown in FIG. 4B, so that the ink adheres permanently to
the receptor coating. A radiant or hot air heater may be applied to
the back of transfer material before the transfer roll to aid in
heating the ink to the preferred operating temperature. When the
substrate has a consistent cross-section in the longitudinal
direction, paper is the preferred transfer material because it is
not required to, and preferably should not, stretch. On exiting the
transfer zone the transfer material is removed by mechanical or
vacuum means. It may be advantageous to slit the transfer material
and use two or more removal flows for higher process efficiency.
The substrate at this point is imaged and ready for
top-coating.
[0057] When the substrate cross-section varies both in the
direction of process flow, and across the direction of process
flow, the dye sublimation transfer process again requires that the
transfer material be matched with the substrate to form a sandwich
prior to the transfer. The matching requires the transfer material
to take on a three-dimensional shape, which in turn requires it to
stretch and/or shrink to conform. A transfer material derived from
cellulosic materials is generally unsuited for this use as it lacks
suitable stretch. Transfer materials derived from plastic materials
such as polyolefins and polyesters are preferred, whether in film
or fibrous form. This matching to form the sandwich is accomplished
with a top platen, or series of top platens, that closely fits the
shape of the substrate. When there is only one platen and it also
functions as the heated platen which effects the conditions for dye
sublimation transfer, that is, a dwell at 300 to 400.degree. F., 20
to 60 sec and 5 to 100 psi. Alternatively, and preferably, the
conforming is effected by a first platen or a first series of
platens that operates at a temperature and pressure sufficient to
mold the transfer material to the shape of the substrate yet not
initiate transfer. When the transfer material is a polyolefin this
may occur at temperatures between 200 and 300.degree. F. The
sandwich of transfer material and substrate then is inserted or
drawn into the press where there is a top platen which presses the
transfer material to the substrate under the conditions preferred
for dye sublimation transfer, 300 to 400.degree. F., 20 to 60
seconds and 5 to 50 psi. After this the sandwich is removed from
the press, the spent transfer material is removed and the object is
ready to move to the next stage, typically top coating.
[0058] When pressing objects with variable topography, removal of
the air between the transfer material and the receptor coat becomes
more difficult. While it may be considered advantageous to use a
porous transfer material carrier, this approach tends to
contaminate the platen with dye that may interfere with subsequent
images, especially if the pattern in use is not being repeated in
tight registration. The steps in bringing the transfer material
into close conformation with the non-planar surface of the
substrate are, therefore, chosen so that air is expelled and not
trapped. Such a pre-application system may be a relatively soft
compliant platen, or it may be a series of compliant platens,
shaped so that air is steadily squeezed out. Alternatively, the
pre-application system may be in the form of a roll or series of
rolls that progressively squeezes out the air. When a
pre-application system is not used, the top platen may comprise a
relatively conformable material, such as a silicone rubber shaped
so that contact is made in a way that does not trap air, or it may
be a flexible platen attached to a belt so that the air is
sequentially squeezed from between the transfer material and the
receptor coating of the substrate. Note that an electrostatic
charge can be used to assist adhering the image transfer material
web to the substrate--the two are charged oppositely by ionized air
or similar charging device.
[0059] As will be appreciated by those skilled in the art, the size
and shape of the contours of the substrate affect both the speed at
which the substrate can be processed and the quality of the
transferred image. For example, grooves with walls at low angle to
the plane of the top surface can be processed readily, but those
with steep walls are more difficult. Similarly, angles and corners
that are rounded process more readily than those that are square or
sharp. The balance between design and process efficiency will in
large part dictate which of the above described image transfer
methods are acceptable for a given project.
[0060] Now referring to FIG. 4C, a cross sectional view of a
product 430 produced by the dye sublimation processes 400 and 450
of FIGS. 4A and 4B in accordance with the present invention is
shown. The finished product 430 includes a base wood or wood
composite substrate 432 having a recess 434, which can be any
multidimensional surface, such as moldings, routings or inserts,
that are above or below the main surface of the base substrate 432.
A layer of stain 436 is on the top surface of the base substrate
432 and a layer of sealant 438 is on the top surface of the stain
layer 436. Note that the stain layer 436 and the sealant layer 438
are optional layers applied during the substrate pre-finishing
process 206 (FIG. 2). The receptor coat 440 is applied to the top
surface of the sealant layer 438 during the receptor coating
process 210 (FIG. 2). As described in reference to FIG. 3A, the
dyes 442 forming the desired image are within the receptor coat
440. The topcoat 442 is then applied on the top surface of the
receptor coat 440 during the top coating process 214 (FIG. 2). The
receptor coat 440, dyes 442 and topcoat 444 are required for the
present invention. Although reference is made to the top surface of
the various layers, the applicable surface is any portion of the
base substrate 432 on which an image is to be transferred. In other
words, "top surface" could actually refer to the top, bottom,
sides, ends or other surface of the base substrate 432. In
addition, the layers described above may apply to some or all
surfaces of the base substrate 432.
[0061] Referring now to FIG. 5, an ink transfer process 500 in
accordance with the present invention is shown. In the ink transfer
process 500, all the ink 502 is transferred from the transfer
material 504 to the receptor coat 506 by hot lamination. More
specifically, the wood or wood composite substrate 508 enters the
process 500 at point A. At point B, ink 502 is transferred from the
transfer material 504 to the receptor coat 506 by means of a heated
roller 510 that applies sufficient pressure to transfer material
504 and receptor coat 506 to cause the ink 502 to transfer to the
receptor coat 506. The transfer material 504 is unwound from a
supply roll 512, transported across roller 510 and rewound on take
up roll 514. At point C, the image formed by inks 502 has been
transferred to the receptor coat 506 of substrate 508.
[0062] Transfer materials 504 suitable for saturation may be
printed by traditional analog means (gravure or flexography) as
well as now by digital processes (e.g., ink jet) so the advantages
of each process can be considered in determining that which is most
appropriate for any situation. A clear coating may also be
transferred from the transfer material 504 to give a wear coat or a
coating for later staining. The wear coat will be sufficiently
durable to ensure the image is not damaged during subsequent
processing or transportation, yet be amenable to over-coating with
a highly durable topcoat. Either a plastic film or a paper may be
used as the transfer material 504 to carry the transfer image.
Paper is preferred for economy. It is important that the transfer
material 504 be processed without wrinkles or creases. The means to
achieve this have been previously described. The transfer material
504 has a release surface which has sufficient adhesion to hold the
ink during manufacture and processing, yet sufficient release to
allow complete transfer of the image when the ink is firmly bonded
to the receptor coat 506 during the image transfer step. Such
transfer materials 504 are said to have "tight release" and are
well known to those familiar with the art.
[0063] This process provides good resolution, crisp images, a very
large color gamut and true metallic colors. In addition, any heat
stable colorant can be used. For example, if the colorants
typically chosen for automotive and exterior building paints are
selected, the finished article can be used for extended long term
outdoor applications. Ink transfer also allows the designer to
select both opaque and transparent inks. Thus, an opaque white ink
may be used as background for a pattern when it is not desired to
have a fully white substrate. This can obviate the need to apply an
opaque white base coat which can be used to advantage for cost or
design purposes, for example when a picture is desired over a part
of a simulated wood grain surface. A further advantage is that the
transfer material 504 for the ink is itself a release sheet.
Therefore, it will not adhere to a gel, soft or partially cured
receptor coating and so the method may be used to image or decorate
surfaces with such characteristics. Ink transfer is typically
applied with a rubber covered roll 510, which extends the image a
small distance around corners of small radius. Thus, if two
adjacent surfaces are imaged, the pattern need not show a seam or
joint, and this advantageously differentiates this process from
veneer or lamination. The image can wrap edges and ends and is
thin--seldom more than 0.5 mils. Moreover, this process 500 only
requires moderate processing conditions (from room temperature to
300.degree. F. depending on the materials used). The process 500 is
readily processed at moderate speed on roll transfer equipment.
[0064] Ink transfer typically is processed at what are considered
moderate conditions--typically 200 to 300.degree. F., and at speeds
up to 100 fpm. It is, therefore, not stressful on most of the
substrate compositions contemplated in this invention.
Nevertheless, steps such as differential heating from top to bottom
may be required to ensure flatness and stability of the substrate
508. The transfer material 504 for ink transfer imaging can be
prepared by digital means such as ink jet or electrography (in
which case the toner functions identically to ink). Thus proofs,
prototypes, demonstration articles and short runs can all be
produced economically.
[0065] Now referring to FIG. 6, a direct printing process 600 in
accordance with the present invention is shown. In the direct
printing by contact process 600 (e.g., flexography or gravure), the
image is from a roll 602 to the receptor coat 604. Gravure printing
uses a hard metal surfaced roll and has the advantages of high life
and high resolution graphics. However, the hard roll is unforgiving
of variations in the thickness of planarity of the substrate and so
is prone to misses and gaps. Flexography uses rubber rolls for the
transfer and so is less susceptible to the consequences of slight
substrate deformation. However, it is more likely to demonstrate
wear from extended use. More specifically, the wood or wood
composite substrate 606 enters the process 600 at point A. At point
B, ink 608 is transferred from the roller 602 to the receptor coat
604 by direct contact. At point C, the image formed by inks 608 has
been transferred to the receptor coat 604 of substrate 606.
[0066] Referring now to FIG. 7, a non-contact ink transfer process
700 in accordance with the present invention is shown. In the
non-contact image transfer process 700 (e.g., inkjet), a large
number of nozzles contained in a print head 702 that transfer ink
704 directly to the receptor coat 706. More specifically, the wood
or wood composite substrate 708 enters the process 700 at point A.
At point B, ink 704 is transferred from the print head 702 to the
receptor coat 706. At point C, the image formed by inks 704 has
been transferred to the receptor coat 706 of substrate 708. Note
that this process 700 does not work well with non-planer surfaces
and tends to slow relative to the other processes. Nozzle problems
may also occur from time to time. Nevertheless, ink jet printing
will be the preferred process for select applications. In
particular it will be chosen when a small amount of variable data
or imagery is to be added to an otherwise repeating image. It may
therefore be used in conjunction with any of the above-mentioned
imaging methods.
[0067] Now referring to FIG. 8, a lamination transfer process 800
in accordance with the present invention is shown. In the
lamination image transfer process 800, the laminates are typically
produced by first printing the image 802 directly on to the face of
a special grade of paper called saturating paper 804, then
saturating the paper with the liquid form of the polymer used for
the laminate, laying the paper on the substrate, and then curing
the sandwich. A suitably saturated paper 804 can be laminated onto
the gel formed from partial cure of the receptor coat 806 and the
topcoat prior to final curing. More specifically, the wood or wood
composite substrate 808 enters the process 800 at point A. At point
B, the saturating paper 804 is transferred from the roller 810 to
the receptor coat 804 by direct contact. The saturating paper 804
is then cut to fit the substrate 808. At point C, the saturating
paper 804 containing the image 802 has been transferred to the
receptor coat 806 of substrate 608. Note that since a layer of
paper applied to the wood or wood composite substrate 808, edge
effect can occur unless the paper is applied full width. In
addition, the saturating paper 804 inherently has a lower
resolution than some of the other image transfer processes.
[0068] Referring now to FIGS. 9A and 9B, cross sectional views of a
product 900 and 950 produced by a ink transfer, lamination, direct
transfer or non-contact transfer process in accordance with the
present invention are shown. The finished product 900 includes a
base wood or wood composite substrate 902 that has a layer of
sealant 904 on the top surface of the substrate 902. The sealant
layer 904 is an optional layer applied during the substrate
pre-finishing process 206 (FIG. 2). The receptor coat 906 is
applied to the top surface of the sealant layer 904 during the
receptor coating process 210 (FIG. 2). As described in reference to
FIGS. 5, 6, 7 and 8, the inks 908 forming the desired image are on
top of the receptor coat 906. The topcoat 910 is then applied on
the top surface of the receptor coat 906 during the top coating
process 214 (FIG. 2). The receptor coat 906, inks 908 and topcoat
910 are required for the present invention. Although reference is
made to the top surface of the various layers, the applicable
surface is any portion of the base substrate 902 on which an image
is to be transferred. In other words "top surface" could actually
refer to the top, bottom, sides, ends or other surface of the base
substrate 902. In addition, the layers described above may apply to
some or all surfaces of the base substrate 902.
[0069] The finished product 950 includes a base wood or wood
composite substrate 952 having a recess 954, which can be any
multidimensional surface, such as moldings, routings or inserts,
that are above or below the main surface of the base substrate 952.
A layer of sealant 956 is on the top surface of the substrate 952.
Note that the sealant layer 956 is an optional layer applied during
the substrate pre-finishing process 206 (FIG. 2). The receptor coat
958 is applied to the top surface of the sealant layer 956 during
the receptor coating process 210 (FIG. 2). As described in
reference to FIG. 3A, the inks 960 forming the desired image are on
top of the receptor coat 958. The topcoat 960 is then applied on
the top surface of the receptor coat 958 during the top coating
process 214 (FIG. 2). The receptor coat 958, inks 960 and topcoat
962 are required for the present invention. Although reference is
made to the top surface of the various layers, the applicable
surface is any portion of the base substrate 952 on which an image
is to be transferred. In other words, "top surface" could actually
refer to the top, bottom, sides, ends or other surface of the base
substrate 952. In addition, the layers described above may apply to
some or all surfaces of the base substrate 952.
[0070] The embodiments and examples set forth herein are presented
to best explain the present invention and its practical application
and to thereby enable those skilled in the art to make and utilize
the invention. However, those skilled in the art will recognize
that the foregoing description and examples have been presented for
the purpose of illustration and example only. The description as
set forth is not intended to be exhaustive or to limit the
invention to the precise form disclosed. Many modifications and
variations are possible in light of the above teaching without
departing from the spirit and scope of the following claims.
* * * * *